LEARN. PRACTICE. GROW.Choose the mechanism around the application contract
Distinguish storage copying, partner exchange endpoints, and the file system consumed by the application. DataSync automates transfers between supported locations; Transfer Family provides managed interfaces such as SFTP. A job requiring a shared NFS path, POSIX permissions, and concurrent access needs compatible storage, such as EFS when other requirements fit. Moving bytes into S3 objects does not establish that the job retains the same semantics. In the fictional example, Autosys triggers processing after a monthly CFT file arrives. Inventory producer, actual protocol, name, completion signal, identity, calendar, consumption, and reconciliation. Do not assume that offering SFTP automatically replaces every behavior of a CFT product. The partner and APS must demonstrate the new end-to-end contract.
Make scope verifiable evidence
DataSync filters are case sensitive and relative to the source location path. If the source is /feeds and the include filter is /close, scope points to /feeds/close; it is not an independent absolute path. In the exercise, /Close does not match that same filter. A manifest also limits selected objects. Even Verify all data is limited to manifest entries when a manifest is used. Confirm the business-required population before interpreting the technical result. A monthly file absent from the manifest does not become verified because all listed files passed. Retain manifest version, exclusions, and an owner for each exception. This lets the committee understand exactly which population was transferred and what remains pending.
Separate bytes, metadata, and destination policy
Configuration determines whether source changes replace existing destination data and whether destination-only files are preserved. OverwriteMode NEVER retains existing content even when the source changed; PRESERVE for deleted files does not make the destination an exact mirror. Choose according to the contract and assess risk before enabling removal. Ownership, POSIX permissions, and ACLs have options and support depending on the locations. OWNER_DACL does not copy SACLs; equal bytes do not establish correct access or access auditing. For a Linux job, validate with the actual service user, including required read, write, and execute operations. For a Windows share, confirm DACL/SACL requirements and transfer-user permissions. Avoid fixing access by globally opening permissions during cutover.
Interpret verification and close the operational loop
DataSync checks integrity during transfer. NONE skips additional end verification; it does not mean absence of every checksum. ONLY_FILES_TRANSFERRED checks transferred data; POINT_IN_TIME_CONSISTENT is unsupported in Enhanced mode and has other destination restrictions. The mode name does not turn files into an application transaction. If a producer changes two related files while copying runs, obtain a consistent boundary through a validated mechanism such as a supported snapshot or authorized pause. Budget time for final copying, verification, and functional rehearsal. An estimate of 240 decimal GB at 80 MB/s gives 50 minutes for transfer alone, excluding overhead; it does not fit a 40-minute window. RUN handover requires correct consumption, alerts, reconciliation, credentials, and a return plan, not just a copied-byte report.
Original transfer estimate; decimal units, no overhead
Required final copy: 240 GB = 240000 MB
Observed transfer rate: 80 MB/s
Transfer only: 240000 / 80 = 3000 s = 50 min
Approved window: 40 min
Gap before verification/application tests: at least 10 minCopying /feeds/close passed, but /feeds/Close contains the required monthly file. Technical success does not cover the missing population.
Common pitfalls
Confusing copying with functional migration; treating a manifest as complete inventory without review; assuming ACL preservation because bytes match; omitting verification from the window.
Related topics: DMS replication and cutover evidence
The result is sufficient only when it covers required files, semantics, and business cycles.
Reference: DataSync integrity verification · SAP-C02